FAMILY STURIONID.E — ACIPENSER. 347 



central rays longest ; its tip reaching the lower base of the caudal. Caudal fin with its upper 

 lobe elongated. 



Color. Dark olive-grey above, occasionallv brownish ; beneath light ash-grey. Fins often 

 red from infiltration. Pupils black ; irides golden yellow. 



Length, 18 '0. 



Fin rays, " D. 38; P. 28; V. 31; A. 23; C. 12.5" {Lcsueur). 



This species appears to grow to a larger size than the preceding. The greatest differences 

 in the characters of the old and young appear to consist in the variable number of die tuber- 

 cles. It would belong to the genus Hclopcs of Brandt, which is thus characteriz.ed ; " Snout 

 " long (one sixth or seventh the length of the body), and body covered with strong bony dis- 

 " tant shields." It forms a palatable food. 



(EXTRA-LIMITAL) 



A. iransmontanus. (Richardsox, 1. c. p. 278, pi. 07.) Prolile shriving off suddenly before the nos- 

 trils, into the greatly depressed and slightly upturned, moderately acute snout, which, measured 

 from the orbits, is -^ of the total. Columbia, River. 



A. rvqiertianus. (Id. I.e. p. 311, pi, 97.) Snout narrow, not acute; its sides flattened ; its vertical 

 height cipial to half the transi-crso breadth. D. -10 ; P. 40 ; C. 112. Length t\vo feet. Northern 

 Regions. 



A. maculosus. (Lesueur, 1. c. Vol. 1, p. 393.) Snout much elongated. Color reddish olive, with black 

 spots. Length six to eighteen inclics. Ohio River. 



Genus Platirostr.\, Lesueur. Jaws, tongue and throat without teeth. Snout long, flattened and 

 spatuliform. Body without plates. Tail only covered on each side by small bonj- plates. 



P. edentula. (Lesueur, Ac. So. Vol. 1, p. 228; Say, App. Long, p. 2o4.) Snout not so long as 

 one-third of the body, dilated and rounded at its end. Opercle long and pointed. D. 58 ; P. 26 : 

 C. 15.84 = 99. Length three to four feet. A specimen in the Albany In.stitute, from Juliet. 

 Illinois. 



